Synthesis gas (syngas) is mainly obtained by partial oxidation of hydrocarbon, usually methane. This process is represented by a cathedral oven provided with tubes containing a catalyst through which methane and steam flow to convert these reactants into CO and H2, i.e. syngas. The purpose of the oven is to heat the tubes by heat radiation to reach the reaction temperatures up to 800° C. Syngas is then cooled down and separated down stream the oven. In alternative syngas is produced from coal gasification. The gasification reactor is fed with coal oxygen and steam to achieve a syngas stream by partial oxidation reaction of the coal itself. Nowadays gasification is technologically feasible also for biomasses and agricultural/industrial residues or solid urban waste, but substantially with the same finality to partially oxidize the reactants in order to obtain syngas.